DARPA Works to Perfect Self-Forging, High-Velocity 'Spears'

By Bill Christensen |
April 29, 2008 06:43am ET

MORE

In his 1955 novel Earthlight, science fiction author
Arthur C. Clarke thought of an incredible superweapon that used giant
electromagnets to shoot a stream of molten metal at lightning speed. Now, the
Defense Advanced Research Projects Agency (DARPA)
wants one for America's military.

They are calling it MAHEM, which stands for Magneto
Hydrodynamic Explosive Munition. The intent is to create a device that creates
a powerful enough electromagnetic field to propel streams of molten metal at
enemy armor. If it works, the device will be a big improvement on a technology
that got its start in World War II  the self-forging penetrator.

Self-forging penetrators, as they are currently used, result
from a conventional chemical explosion directed against a specially-shaped
metal liner. When the device is set off, the blast causes the metal liner to
achieve a new shape, suitable for penetrating deep into even moderately armored
vehicles, and driven forward at a high velocity. The technology dates back to
WWII.

This kind of weapon can be highly effective (it is currently
being used against troops in Iraq). The drawbacks of this kind of weapon from
the standpoint of US military planners is that they are one-time-use weapons,
and cannot efficiently form multiple SFPs from a single charge.

If it is possible to use a powerful electromagnet to
accelerate a molten jet of metal, it could overcome the drawbacks mentioned
above, and even achieve higher velocities and better targeting. DARPA hopes
that it could provide the following capabilities:

"This could provide the warfighter with a means to
address stressing missions such as: lightweight active self-protection for
vehicles (potential defeat mechanism for a kinetic energy round), counter armor
(passive, reactive, and active), mine countermeasures, and anti-ship cruise missile
final layer of defense."

Science fiction readers wonder what took DARPA planners so
long; we've known about this idea for more than a half-century. In Earthlight,
Arthur C. Clarke makes use of exactly this idea in a battle between a
stationary facility on the Moon and several attacking space ships, including
the aptly named Lethe.

Listen to the incomparable Clarke describe the battle for
you, which takes place in the Sea of Rains.

"In
utter silence, the battle was rising to its climax. Millions of years ago the
molten rock had frozen to form the Sea of Rains, and now the weapons of the
ships were turning it once more to lava. Out by the fortress, clouds of
incandescent vapor were being blasted into the sky ...

"Wheeler
saw it strike upward, a solid bar of light stabbing at the stars... He did not
have time to reflect on the staggering violation of the laws of optics which
this phenomenon implied, for he was staring at the ruined ship above his head.
The beam had gone through Lethe
as if she did not exist; the fortress had speared her as an entomologist
pierces a butterfly with a pin."
(Read more about the stiletto beam;
see illustrative
book cover.)

The "beam" was a molten jet of metal hurled into
space by enormous electromagnets.

This is not the only example of science-fictional weaponry sought by US government agencies: